Impatiens Care: Watering, Feeding and Keeping Plants Bushy All Season

The dramatic wilt is information, not an emergency

An impatiens short of water does not sag gently. It goes completely flat, leaves hanging straight down, stems folded over the rim of the pot, looking as though it died overnight. Almost everyone who grows them for the first time throws one away in that state. Water it thoroughly instead and watch: the stems lift within twenty minutes, the leaves are horizontal again inside an hour, and by the following morning there is no sign anything happened. The plant is roughly nine tenths water in soft green tissue with no woody structure at all, so it loses turgor faster and regains it faster than anything else in the garden.

This makes impatiens the most readable plant you can grow. You do not need a moisture meter or a schedule, because the plant raises its hand. What you do need is to respond quickly, because the tolerance is not infinite. One collapse and one recovery costs you nothing. A plant that has been left flat in full afternoon sun for several hours comes back but sheds every open flower and most of its buds, and takes ten days to start flowering again. A plant that has collapsed three or four times over a fortnight starts losing lower leaves permanently and never fills back out.

So use the wilt as an early warning and then arrange things so it stops happening. A collapse every afternoon in high summer means the pot is too small, the plant is in too much sun, or the compost has shrunk away from the sides and the water is running down the gap without wetting anything. Check for that gap by watering and seeing how fast it comes out of the base; if it drains in three seconds, the root ball is bone dry inside and needs standing in a bucket of water for twenty minutes to rewet properly.

Water often, feed lightly, and keep the leaves dry

In the ground in shade, a soak twice a week through warm weather is usually enough, and in cool damp spells rain covers it entirely. In containers the demand is much higher: a full hanging basket in summer needs water every day and sometimes twice, because the root ball is small and the plant is transpiring hard through a large area of soft leaf. Water until it runs freely from the drainage holes, then leave it until the surface is dry again rather than sprinkling little and often.

Water at the base of the plant, not over the top. This matters more for impatiens than for most bedding plants because the leaves are thin and the crown is dense, and standing moisture on the foliage overnight is what gets downy mildew started. If you use a hose over a bed, do it in the morning so everything is dry by dusk.

Feeding is where people overdo it. Impatiens grow fast and it is tempting to push them harder, but heavy nitrogen gives you a big soft plant with dark leaves and hardly any flowers, and that soft growth is far more attractive to aphids and far more prone to mildew. A balanced liquid feed at half strength every two weeks is right for containers. Plants in decent garden soil with compost forked in often need nothing at all for the first six weeks. If your plants are all leaf and no bloom, stop feeding for a month rather than switching product.

Write down how often each container actually needed water in the hottest fortnight of the year. Next season that number tells you immediately which baskets are too small and which positions are unworkable without daily attention, which is far more useful than any general watering advice.

No deadheading, but pinch to keep the shape

One of the real pleasures of impatiens is that you never deadhead them. A finished flower detaches cleanly at its own joint and falls off, taking its stalk with it, and the plant carries on producing without any prompting. There is no seed pod left behind to switch off flowering, which is why they bloom continuously from planting until the first frost with no intervention at all. You will find the fallen flowers on the soil below and on the patio, and that is the whole of it.

What they do need instead is pinching. Left alone, a young plant runs upward on a few long stems and ends up tall, thin and open, with flowers only at the tips and bare stem showing at the base. Pinch the growing tip out of each main stem when the plant is around six inches (15 cm) tall, taking the top half inch (12 mm) with your fingernails just above a pair of leaves. Two shoots break below each pinch within a week, and the plant becomes twice as dense at the cost of about ten days of flowering.

Mid season, if a plant has stretched anyway, cut the whole thing back by a third. This looks brutal on something that is flowering, and it is the correct move: impatiens regrow from the cut stems faster than almost anything, breaking new shoots in five to seven days and flowering again in two to three weeks, denser than before. Do it on a mild day, water well first, give a half strength feed straight afterwards, and do not cut back into bare leafless stem with no growth points on it.

1. Pinch the tips at six inches (15 cm) Take out the top half inch (12 mm) of each main stem just above a pair of leaves. Two shoots break below each cut, which doubles the number of flowering points.
2. Leave fallen flowers where they land on the soil Nothing needs deadheading. Do clear any that lodge in the crown of the plant though, because wet spent flowers sitting among the stems are where rot and mildew begin.
3. Cut back by a third if the plant stretches Reduce leggy plants above a leaf pair, leaving at least two leafy joints on every stem you shorten. Water well the day before and feed lightly after.
4. Turn containers a quarter turn weekly Impatiens lean hard toward the brightest side. A weekly quarter turn keeps a pot or basket flowering evenly all the way round instead of on one face.
5. Keep mulch clear of the stems Mulch the bed to hold moisture, but leave two inches (5 cm) of bare soil around each plant. Mulch heaped against soft stems causes rot at the base.

Shade, heat and the end of the season

Impatiens are shade plants, which is most of why people grow them, and they flower more heavily in partial shade than anything else you can put under a tree. Full morning sun with shade from midday onward suits them best. In deep shade they keep flowering but the plant stretches, the stems lengthen between leaves, and the flower count drops by half. In full afternoon sun in a hot climate they scorch at the leaf edges, wilt daily and stop blooming.

They also have no frost tolerance whatsoever. Not reduced tolerance, none. A light frost that leaves everything else looking fine turns impatiens to black mush overnight, and there is no recovery. If you want to keep a plant, take cuttings in late summer while the weather is still warm, because there is no way to protect a plant outdoors once the temperature reaches freezing. Bringing a whole plant indoors works but it needs a bright window and it will drop most of its leaves adjusting.

Through the warmest weeks a plant will slow down, and the response is water and shade rather than feed. Once the nights start cooling in early autumn the flowering often improves noticeably for a few weeks, and that late flush is the best of the year. It ends abruptly with the first frost, and it is worth knowing the plants will be gone in a single night rather than fading away, so cuttings and any tidying happen before that night rather than after.

Note the date of the first frost that killed your plants and the date you took cuttings. Cuttings taken two weeks before that frost root easily in warm conditions; cuttings taken in the week before it often sit and rot, so the gap between those two dates is what you are trying to get right.